Temperature indicator



Nov. 26, 1935. F. M. SLOUGH' 2,022,440

TEMPERATURE INDICATOR Filed N66. so. 1928 Patented Nov. 26, 1935 UNITED-STATES PATENT OFFICE i 2,022,440 TEMPERATURE INDICATOR Frank M. Slough,Cleveland, Ohio, assignor to The Anderson Company Application November30, 1928, Serial No. 822,905 4 Claims. (Cl. 177-451) instrument board ofa motor vehicle, the tem-- perature of the cooling fluid for the enginefor the vehicle.

An object of my invention is to reliably indicate temperature remotelyfrom the point where the temperature condition to be indicated exists.

Another object of my invention is to provide a remotely disposedindicating mechanism for indicating temperatures and/or pressurescomprising separate operating and indicating units, the operating unitexercising control over the indicating unit, by virtue of an electricalcircuit interlinking the two.

Another object of my invention is to provide mechanism of the above typewhich will be reliable in use and which can big/manufactured at lowcost. I

Other objects of my invention and the invention itself will becomeapparent by reference to the following description of severalembodiments of my invention, which are illustrated in the ac- Icompanying drawing.

Referring to the drawing: Fig. 1 illustrates a system comprisingacontrolling unit and an indicating unit applicable to an automotivevehicle to remotely indicate the temperature of the engine coolingfluid, to-

gether with associated electrical circuit conducbodiment controllingunit for the system of Fig. 1.

I gine jacket wall I.

ly extending rim flange ,6, anapertured disk 8 of heat insulating, heatresisting material, such as asbestos board secured thereto by spacedrivets I.

A flanged tubular casing 9 is securely mounted 5 on the disk 8 by rivetslli projected through its flange and disk. A can i I is screw threadedonto the end of the casing 9. 0n the interior of the casing, anelectromagnet l2 and a thermostatic warpable strip II are carried, thelatter being 10 carried by anend, while thermally insulated from thecasing 9, on a supporting block H of heat and electrical insulatingmaterial secured .to the inner wall of the casing. The strip i3 carriesan armature l5 for an electromagnet ,I2, 1 the armature being spacedfrom the adjacent pole of the magnet core, and an electrical heatingelement It comprising a few convolutions of resistance wire, is placedclosely about a limited length of the strip I3, preferably near its sup-20 p rt ll.

Within the supporting shell 4, a metallic plug I1 is disposedhaving anand projected between the jacket walls I and 2, and immersed in Sthecooling fluid 3. 'The plug I1 is provided with 25 external threads onits immersed projecting end, on which a clamp nut i8 is threaded tocooperate with the flanged head IQ of the plug to securely clamp theplug in position on the shell l.

Suitable interposed heat insulating washers 20 and 2| and a heatinsulating bushing 22 rev stricts the flow of heat from the metallicwalls of the shell 4 to the plug II, while the end of the plug and thecarried clamping nut 18 collects heat from the surrounding fluid I.

The plug l1 and the nut II are preferably of copper or other eflicientheat conducting material while the shell 4 and casing 9 together withthe cap Ii are preferably of soft steel, and the outer surface 23 of theshell 4 is preferably made polygonal to facilitate screw threadingitinto the en- A fluid sealing gasket 24 is interposed between ashoulder of the shell and the wall I. v

A heat conducting metallicholder 28 having a threaded stem 34 and anenlarged bifurcated head 35. is screw threaded by its stem into an endrecess of the plug II.

An end of a bi-metallic thermally warpable strip 26 is rigidly securedbetween the forks of the head 35, by one or more rivets 21 passedtherethrough and through the strip. The free end of the strip 2 extendslongitudinally from 'the shell 4 into the tubular casing 0, throughaligned elongated apertures 20- and 30 of the heat 66 insulating disks 8and 3|, the latter disk being interposed between the disk 8 and thestrip holder 25. The free ends of the strips l3 and 24 are juxtaposedand each carries a contact element made of platinum, silver, or thelike, as illustrated at 32 and 33 respectively. During operation of thecontrolling unit, these contacts are intermittently moved to currentconducting engagement as will be later, herein, related.

One of the contacts, such as the contact 33, is preferably mounted onthe end of an adjusting screw 36, whereby the contacts 32 and 33 may berelatively adjusted, access to the screw 36 for adjustment being hadthrough the wall of the casing 9 by first removing a closure plug 31,nor-* mally screw threaded into the wall.

The electromagnet 12 preferably comprises a winding 38 of a relativelyfew number of turns of wire, when the winding is placed in serialcircuit with the heating element It, as illustrated. Circuit conductorssuch as the conductor 50, will extend between the controller and theindicator, shown in the top portion and lower portion, re-, spectively,of Fig. 1. Other circuit conductors such as the conductor leading to theignition circuit 52, and ignition switch 48, and 53 leading to thestorage battery 41, will be well understood.

However, the magnet winding 38 may be placed in multiple circuit withthe winding ll instead of serial circuit, and the number of turns in thewire 38 will be accordingly modified in such a case, so as to limit theenergization of the magnet and the diverting of current from the heatingelement It. Bi-metallic strips 26 and I3, when exposed to heat, are eachadapted to move in the same direction, indicated by the arrows 33 and 43on the drawing'of Fig. 1.

Although the precise form of the indicating instrument may be widelyvaried, the indicator shown at 8! comprises a pointer 42 pivoted at 43and having a short bifurcated end 44, its other pointing end adapted totraverse a scale which may be graduated to degrees of temperature, or asin the scale illustrated at 33, may merely contain legends such as Cool,Normal and Hot.

The actuating means for the pointer 42 comprises a bi-metallic thermallywarpable strip 46 supported by a fixed end and carrying by its free enda compensating bi-metaliic thermally warpable strip 45 ,which projectsbetween the forks of the pointer portion 44. The actuating andcompensating strip sections 46 and 45 respectively, are preferablythermally insulated from each other by the joining pieces 80 ofpreferably heat' insulating material, the pieces being riveted orotherwise secured to the strips at their adjacent ends.

Although the heating element 4| may comprise merely a few turns ofresistance wire winding on the strip 46 after the manner of theralstance wire it on the strip l3 of the controller apparatus, I maysometimes provide a. metallic spool 4| rigidly carried on a block ofinsulating material 32, V which in turn is carried by the frame of thelndi-j of such mass as to provide ample heat storage capacity wherebywhen electrical current flows intermittently through the' resistancewinding placed on the spool under the control of the electrical contacts3233, the heat received during 5 each current impulse will be largelystorage and continuously supplied to the strip 46.

The strips 45 and 46 are oppositely disposed relative to the dispositionof their bi-metallic laminated components, such as brass and steel,placed face to face throughout their. lengths, so that upon both stripsbeing heated they will warp their ends in opposite directions.

The compensating strip 45 is made of such a length and of such a.thickness that when both strips are alike subjected to the sameatmospheric temperature, the opposite warping effects of the two willsubstantially exactly counter-balance, and the free end of the strip 45will not effect movement of the bifurcated end of the pointer.

However, electrical heating is only communicated to the strip 43 and itwill alone warp when electrically heated, moving the free end of thestrip 45. r

The storage battery 41, for the automotive veas hicle, supplies theelectrical current for the system through contacts of the ignitionswitch 43, which is used to control the flow of current from the storagebattery to the ignition circuit and to the temperature indicating systemcircuit.

At 43 the frame of the automobile chassis is indicated,diagrammatically. One of the rivets, such as the rivet I of the group ofrivets I and I3 joining the controller shell 4 and the tubular casing 3to the intermediate heat insulating disk 3, will be understood aselectrically connecting the casing 3 to the shell 4, which in turn makeselectrical connection to the chassis, indicated diagrammatically at 49,Fig. 1.

The parts being arranged as described, the system of Fig. l operates asfollows, it being considered, e. g., that the cooling water 3 hasattained a temperature of 160 Fahrenheit, and responsive to such atemperature, heat communicated to the bi-mefallic strip 28 via the plugll and clamping nut l3 and the bifurcated metallic holder 35, causes thestrip to warp in the direction of the arrow 39, to effect contactbetween the normally separated electrical contacts 33 and 33 carried onthe ends of the juxtaposed 50 strips l3 and 26, and contacts of theignition switch 43 being meanwhile closed during operation of theengine.

It will be assumed, moreover, that these contacts will be closed whenthe temperature communicated to the strip 26, reaches 120, which isarbitrarily selected as being a temperature in I excess of atmospherictemperature. Closure of the contacts will effect energization of theheating elements I3 and 4|, and also the electromagnet II. The onlyeffect of the electromagnet l3, will be to deflect the strip l3, againstthe power of its inherent resiliency, to more firmly press the contacts32 and 33 together, though, as will be later understood, the magnet I2is made to 2,022,440 will continue simultaneously with heating of thesive t0 the temperature of the fluid 3, and depending upon the rate andintensity of heat effected by the heating element I6 upon the bi-'metallic strip I3, the strip I3 will warp its contact carrying end inthe direction of the arrow 30, and against the power of the pressureintensifying magnet I2, until the contact 32 is withdrawn from thecontact 33, whereupon the contacts being initially broken, they willseparate a predetermined distance by a snap-action", by virtue of theinherent resiliency of the strip I3 and the slight deflection effectedupon the strip I3 by" the magnet I2, until the contacts are broken.

This will produce a "quick break of the contacts to materially reducethe arcing at the contacts and will materially increase their period ofusefulness.

The contacts being thus broken, heating of the strip I3 by the heatingelement placed thereupon, will be discontinued and heat being losttherefrom, from all causes such as radiation, convection, andconduction, the thermostatic strip I3 will unwarp sufllciently toreclose the contacfs 32-43, whereupon the operation just described willbe periodically reeflected.

The heat storage capacity of the heating element" and the strip 36, willbe made such that upon momentarily reduced temperatures ,the indicatingpointer will only slightly recede. At the same time, the parts willpreferably be so proportioned that heat indicationsresponsive to thefirst few of a series of periodic energizations of the heating elementll will, in a reasonably limited length of time, eflect warping of thestrip 46 to cause the pointer 42 to advance over the scalepto indicatethe temperature of the enciting liquid 3. The parts will preferably besoproportioned, for most purposes, as to make this period of aboutone-half minute duration.

' The position of the pointer on the scale for any given motortemperature, may be variedby longitudinally adjusting the contactcarrying screw 36 by turning it in the threaded aperture of the strip23, through which it is passed, to determine, first, the temperature atwhich the contacts 32 and 33 engage, and second, the

higher temperature at which these contacts are broken.

Of course during the operation of the device,

the indications will slightly vary, periodically,-

but because of-the eflect of heat storage just described, this variationis slight and not readily" noticeable.

The strip 13 preferably comprises two longitudinally disposed sectionsI30-and I3I joined at adjacent ends preferably by junction means I32 ofrelatively non-heat conducting material. The heating element I6 isdisposed on one of the sections such as the section I30 which is sodisposed relative to the strip 26 attached to the immersion I directionof warping indicated by the arrow 33 a for the strip 23 when heated. Thesection I3I however, if heated, will warp in the-direct ion opposite tothat indicated by the arrow 40.

I find that the heating of the section l3lor the element I3 may beaccomplished without objectionable heating of the section I3I whereastemperature changes of the sections I30 and I3I,

as to length and thermal responsiveness that the carried contact 32 willremain immovable upon changes of temperature of both sections I30 andI3I resulting from changes of ambient temperature only and will moveupon a change of temperature eifected by energization or de-energizationof the heating element I6.

Having described completely one embodiment of my invention, referencewill now be had to other embodiments, such as shown in Fig. .3, whereina controller is illustrated, which is substantially the same as thecontroller of the system of Fig. 1, except that in this embodiment noelectromagnet is employed, and the heating element I3 for the strip I3is included in-serial circuit with the circuit conductor ieading to theheating elements, such as 4 I, as illustrated in Fig. 1, the other partsof the system being preferably'the same as in Fig. 1.

The operation of the controller oi! Fig. 3, is,

in the main, like that of Fig. 1, except that the same degree ofsnap-action" breaking of the electrical contacts 32' and 33', will notbe had in the embodiment of Fig. 3, which, however, is less expensive tomake than the preceding embodiment.

The controlling unit indicated in Fig. 4 is generally the same as thatof Fig. 3 except that the electrical heating element 54 is associatedwith the c ntact carrying section 55 of the bi-metallic strip ratherthan with the fixed section 55'.

Therefore, in the system of Fig. 4, upon changes of atmospherictemperature, the strip 55, carrying a heating element 54 is thermallyinsulated from and warps in an opposite direction to the supportingstrip 55', a heat insulating connector 03 holding the spaced ends of thestrips together.

It will be'understood that upon increases of atmospheric temperature,the strip 55"will warp its free end in the direction indicated by theendin the direction indicated by the arrow 33.

The net result of atmospheric heating, therefore, i would be, assumingthe partsto be properly proarrow while the st'rip 03 will warp its freeY subsequently separated .as described for the 'embodiment of Fig. 3, byelectrical heating of the direction of the arrow 33. The plug 53'supporting the strip 51, communicates heat to it from the liquid 3. Thecircuit.

arrangements in the embodiments of Fig. 4 and Fig. 3 are identical, andexcept for the inclusion .ofthe magnet winding 33 in the system of Fig.1,

the circuit of Fig.1 is also preferably like that of the other figures.

It will be understood also that any of the thermostatic stripsofcontroller or indicator may be arranged in other form, such as-by coil--ing or bending, or. other forms of thermally movable elements may besubstituted, those shown to strip 35 moving its free end. downwardly inthe V being considered, however, most suitable for the purposesindicated herein.

Having thus described my invention as applied to several embodimentcontrollers and indicators operating in two diflerent ways in connectionwith the different controllers, I am aware that numerous and extensivedepartures may be made irom the controlling and indicating mechanismsand systems as above described, but without departing from the spirit ofmy invention, and that controllers and/or indicators, varying widely inspeciflc design from those herein shown may be substituted therefor.

Also that such may be used in connection with the indicator and/orcontroller of any of said embodiments illustrated herein, or within thepurview of my invention, but without departing from the spirit oi. myinvention.

I.claim:

1. An electrical controlling mechanism for a temperature indicatingsystem comprising a two-part casing, thermal insulating means joiningthe casing parts, one of said parts terminating in a heat conductingplug adapted for projection through an aperture of a fluid container forexposure to the temperature oi fluid therein, the other casing partsupplying -a thermostat chamber, -a pair of bimetallic thermostats andan electrical controller in the thermostat chamber, diflerentiallyoperable by said thermostats, one of said thermostats extending by aheat conducting end through said insulating means into the other saidcasing part and thermally joined therein to said plug and responsive toplug temperature, and an electrical resistor heater thermally associatedwith the other of said thermostats.

2. An electrical controlling mechanism tor a temperature indicatingsystem comprising a twopart casing, thermal insulating means joiningthecasing parts, one of said parts terminating in the other casing partsupplying a thermostatchamber, span of bimetallic thermostats, an,

electrical current controller therein dili'erentialiy operable by saidthermostats comprising engageabie contacts supported by the respectivebimetallic thermostats, one of said thermostats extending by a heatconducting end through said insulating means into the other casing partahd thermally joined therein to said plug and responsive to plugtemperature, an electrical resistor heater, thermally associated withthe other or said thermostats, energizable by current passingtherethrough to. heat its associated thermostat eflecting a separationoi the contacts.

3. An electric controller mechanism comprising a two-part casing havingrelatively thermally insulated casing parts, one oi said parts includinga heat conducting plug adapted for projection through an aperture oi afluid container and exposed to the temperature of fluid therein, theother part comprising a thermostat chamber, 'a flrst thermostatthermally joined to the plug and responsive to plug temperature, and asecond electrically heatable thermostat disposed in the chamber andadapted upon engagement with the flrst thermostat to complete anelectric circuit.

/ 4. An electrical controlling mechanism for a temperature indicatingsystem comprising a twopart casing, thermal insulating means joining thecasing parts, one of said parts terminating in a heat conducting plugadapted for projection through an aperture of a fluid container forexposure to the temperature of fluid therein, the other casing partsupplying a thermostat chamher, a pair or bimetallic thermostats, anelectrical current controller therein, diilerentially operable by saidthermostats, one of said thermostats extending by a heat conducting endthroughsaid insulating means into the other casing part and thermallyjoined therein to said plug and resp nsive to plug temperature, theother or said thermostats being compensated for ambient temperature andadaptedupon contact with theflrst said thermostat to complete anelectric circuit.

FRANK M. BLOUGK.

